The invention is directed to changing the functioning of piezoelectric current sensors and energy scavenging devices for use on power systems so as to prolong their useful life and compensate for small power system frequency variations as well as ambient temperature variations that might affect the resonant frequency of the resonant piezoelectric element.
Piezoelectric current sensors are widely used to monitor current flow and energy use in power systems. Often, they are configured with an energy scavenger device that uses energy from the current sources being monitored to make them self sufficient for energy in remote locations. Thus, power cables for example may be monitored in remote locations with low service requirements. One problem that occurs is fatigue of the energy scavengers as a result of prolonged use in service in applications where small power frequency changes result from variations in power demand and supply. Available solutions include mechanical configurations that may adjust the resonance frequency of piezoelectric resonators and transducers to reduce this fatigue. However, these typically require substantial electric power to operate, and may demand too much power from the source being monitored.
Thus, what is needed is a lower power solution to this problem, where the resonance frequency of piezoelectric resonators and transducers can be adjusted to reduce this fatigue. As will be seen, the invention provides such a solution in an elegant manner.